Tuesday 15 December 2009

54 year DDH





54 year DDH with pain rt. hip, Gross trendelenberg gait and 7 cm shortening.

Options
1. Milch Batchelor osteotomy if the patient is financially challenged to avoid trendelenberg gait and excision of the head if one believes that as a cause of pain-
2. THR with a modular stem with subtrochanteric shortening

Problems with THR- Solutions
Finding the true acetabulum- Standard hardinge exept the proximal limb in an acute angle to follow the gluteus medius fibres. Neck osteotomy as planned. Follow the inferior capsule from lesser trochanter to reach the true acetabulum or walk on the ilium with a Homan distally till you slip below the transverse ligament, all the while excising the scar.
acetabulum with narrower AP diameter as compared to supero inferior diameter.Thin or deficient anterior wall.- Drill the medial wall eith a 2.5 drill and measure the depth usually 1 to 1.5 cm. That is how much you can medialise the cup or even break the medial wall as described by Zhiang. Use the next reamers in the inclination and version decided with a posterior vector to ream less of the anterior wall till one gets a good fit not just superior inferior fit. 70% host bone contact is achieved without much ado.
Osteoporotic acetabulum as it was never loaded - .I had a problem in one case when the acetabular dome screws cut out when mobilising the patient and had to cement a cup. So keep Cemented cup back up.

Shortening of femur - well descibed techniques in literature- shall elucidate if needed without boring others with this writen diarrhoea.
Narrow canal
Proximal distal mismatch
2 yr follow up xrays after the weekend
As a reply to Dr. Utkarsh comments. To find the true acetabulum after the osteotomy force the spike of the homan;s spike on the ilium and excise the scar. Walk down on the ilium with the spike feeling the bone till you come to the deficiency inferiorly which is the tear drop.

As far as the stem goes I use a modular stem which is distal fixing and proximal loading with sizes upto 6m and small offset to cover for the narrow canal. The distal slot helps to hold the distal fragment after the shortening osteotomy and rarely a unicortical plate is needed.

There ia a latin american paper where in a distal shorterning osteotomy is in the metaphysis ( supracondylar)with similar results. Others have desribed a method to Intesucept the distal smaller dia fragment to the larger dia proximal fragment for stability. We use a sagital osteotomy of the shortenend excised fragments as a vascularised graft with V. lateralis attached to lie on either side of the osteotomy as seen in the above xrays.



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1 comment:

  1. good elaboration and nice tips for such difficult case.
    majority of the times it is difficult to find the acetabular surface.
    what will be the choice of stem?

    ReplyDelete